package com.test.cordova.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class Base64 {

    static final char[] charTab =  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();

    public static String encode(byte[] data) {
        return encode(data, 0, data.length, null).toString();
    }

    public static StringBuffer encode(
        byte[] data,
        int start,
        int len,
        StringBuffer buf) {

        if (buf == null)
            buf = new StringBuffer(data.length * 3 / 2);

        int end = len - 3;
        int i = start;
        int n = 0;

        while (i <= end) {
            int d =
                ((((int) data[i]) & 0x0ff) << 16)
                    | ((((int) data[i + 1]) & 0x0ff) << 8)
                    | (((int) data[i + 2]) & 0x0ff);

            buf.append(charTab[(d >> 18) & 63]);
            buf.append(charTab[(d >> 12) & 63]);
            buf.append(charTab[(d >> 6) & 63]);
            buf.append(charTab[d & 63]);

            i += 3;

            if (n++ >= 14) {
                n = 0;
                buf.append("\r\n");
            }
        }

        if (i == start + len - 2) {
            int d =
                ((((int) data[i]) & 0x0ff) << 16)
                    | ((((int) data[i + 1]) & 255) << 8);

            buf.append(charTab[(d >> 18) & 63]);
            buf.append(charTab[(d >> 12) & 63]);
            buf.append(charTab[(d >> 6) & 63]);
            buf.append("=");
        }
        else if (i == start + len - 1) {
            int d = (((int) data[i]) & 0x0ff) << 16;

            buf.append(charTab[(d >> 18) & 63]);
            buf.append(charTab[(d >> 12) & 63]);
            buf.append("==");
        }

        return buf;
    }

    static int decode(char c) {
        if (c >= 'A' && c <= 'Z')
            return ((int) c) - 65;
        else if (c >= 'a' && c <= 'z')
            return ((int) c) - 97 + 26;
        else if (c >= '0' && c <= '9')
            return ((int) c) - 48 + 26 + 26;
        else
            switch (c) {
                case '+' :
                    return 62;
                case '/' :
                    return 63;
                case '=' :
                    return 0;
                default :
                    throw new RuntimeException(
                        "unexpected code: " + c);
            }
    }

    public static byte[] decode(String s) {

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        try {
            decode(s, bos);
        }
        catch (IOException e) {
            throw new RuntimeException();
        }
        return bos.toByteArray();
    }

    public static void decode(String s, OutputStream os)
        throws IOException {
        int i = 0;

        int len = s.length();

        while (true) {
            while (i < len && s.charAt(i) <= ' ')
                i++;

            if (i == len)
                break;

            int tri =
                (decode(s.charAt(i)) << 18)
                    + (decode(s.charAt(i + 1)) << 12)
                    + (decode(s.charAt(i + 2)) << 6)
                    + (decode(s.charAt(i + 3)));

            os.write((tri >> 16) & 255);
            if (s.charAt(i + 2) == '=')
                break;
            os.write((tri >> 8) & 255);
            if (s.charAt(i + 3) == '=')
                break;
            os.write(tri & 255);

            i += 4;
        }
    }
}
